#define  _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
struct ListNode {
    int val;
    struct ListNode* next;
    
};
struct ListNode* FindKthToTail(struct ListNode* pListHead, int k)
{
    if (pListHead == NULL)
        return NULL;
    struct ListNode* slow = pListHead;
    struct ListNode* fast = pListHead;
    while (k--)
    {
        if (fast == NULL)
            return NULL;
        fast = fast->next;
    }
    while (fast)
    {
        slow = slow->next;
        fast = fast->next;
    }
    return slow;
}